Concern about symptoms. Reason of symp!

I am  20 years old boy.in last December  I got UTI. after it, I am in shocked and getting anytime worried about a serious disease like if I got stomach pain I thought it is stomach cancer if I got a sore throat I worried that it is throat cancer.i have worried every time. When I was extremely worried first I was used to googling my symptoms and find that my symptoms are related to a tumour, cancer . After it, I have scans, blood tests, ultrasounds, and every time my report comes normal but thought something is missing in this report. Once I got stomach pain and I got MRI stomach And again report was normal. Once I got heavy head, dizziness, and headache I got the MRI brain in January again report was normal .and I am a little bit relaxed for few days But again after some days I again worried that I got a brain tumour in February .now I really have physical symptoms like dizziness,mild headache,neck pain,tight band wrapped and pressure feeling in head everytime.whats the reason of symp